Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

First structure of transporter enzyme family is solved

01.08.2003


Finding will aid drug design to combat depression, stroke and diabetes. Scientists are a step closer to understanding how essential nutrients, vitamins and minerals are ferried into cells.



For the first time, a member of the Major Facilitator Superfamily (MFS) of transport proteins, found in almost every form of life, has been visualised by researchers from Imperial College London and the University of California, Los Angeles.

Reporting in Science today, the researchers reveal the structure of lactose permease, the enzyme in Esherichia coli that helps pump lactose, the major sugar in milk, into cells. Using the structure data, the researchers propose a possible mechanism of action, which is likely to be common among other transport proteins in this family.


Professor So Iwata of Imperial’s Centre for Structural Biology and senior author of the paper explains: "Membrane transport proteins play major roles in depression, stroke and diabetes. Unravelling their structure is critical not only for understanding how we function, but also to improve drug design. Indeed, two of the most widely prescribed drugs in the world, Prozac and Prilosec, act through these proteins.

"The three-dimensional structure of lactose permease gives us our first real picture of how the family of enzymes work. For example, in humans the MFS transporter GLUT4 is responsible for increased glucose uptake in response to insulin stimulation, which has important implications for diabetes. Using the structure of lactose permease we can model GLUT4 and design drugs to control glucose uptake."

Membrane transport proteins play a crucial role in maintaining the selective internal environment of cells. They act as gatekeepers by controlling the entry of nutrients and the exit of waste products. But only four transport protein structures are presently known, compared with over 30,000 soluble protein structures, because they are notoriously difficult to crystallise.

Professor Iwata’s Laboratory of Membrane Protein Crystallography is one of a small number around the world that focuses on determining the three-dimensional structure of membrane embedded proteins.

By combining expertise with Professor Ron Kaback of the University of California, who has been working on lactose permease for 30 years, they have finally solved the structure of this important protein.

Previous biochemical studies had identified six sites within the genetic code of lactose permease that are thought to be crucial to transportation. Using the latest X-ray crystallography techniques, the researchers were able to visualise how lactose permease binds to sugar.

"We have been able to pinpoint areas in the genetic code critical for binding and transport of sugar, which are consistent with information derived from biochemical studies, "said Professor Iwata.

By combining the structural data with previous findings the researchers propose a mechanism of enzyme action.

"Computer simulations show that the enzyme works in a surprisingly simple way. The enzyme is literally gate-keeping. Usually the gate is open towards the outside of the cells and various substances can reach the sugar-binding pocket in the middle of the enzyme, embedded in the cell membrane.

"Only when the enzyme identifies lactose does the other gate, connected to the inside of the cell, open and let the sugar go through. This process is driven by energy called the ’proton motive force’ and should be common among membrane transport proteins."

Professor Iwata added: "Only 40 years ago the idea that genes could be specifically turned on or off in response to different environmental conditions was revolutionary. It was studies in E. coli that showed the bacterial cellular machinery needed to digest lactose is only activated when glucose is not available. Now we have a detailed molecular understanding of how lactose permease contributes to this process."

Judith H Moore | EurekAlert!
Further information:
http://www.imperial.ac.uk

More articles from Life Sciences:

nachricht Selectively Reactivating Nerve Cells to Retrieve a Memory
01.06.2020 | Universität Heidelberg

nachricht CeMM study reveals how a master regulator of gene transcription operates
01.06.2020 | CeMM Forschungszentrum für Molekulare Medizin der Österreichischen Akademie der Wissenschaften

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Biotechnology: Triggered by light, a novel way to switch on an enzyme

In living cells, enzymes drive biochemical metabolic processes enabling reactions to take place efficiently. It is this very ability which allows them to be used as catalysts in biotechnology, for example to create chemical products such as pharmaceutics. Researchers now identified an enzyme that, when illuminated with blue light, becomes catalytically active and initiates a reaction that was previously unknown in enzymatics. The study was published in "Nature Communications".

Enzymes: they are the central drivers for biochemical metabolic processes in every living cell, enabling reactions to take place efficiently. It is this very...

Im Focus: New double-contrast technique picks up small tumors on MRI

Early detection of tumors is extremely important in treating cancer. A new technique developed by researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from normal tissue. The work is published May 25 in the journal Nature Nanotechnology.

researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from...

Im Focus: I-call - When microimplants communicate with each other / Innovation driver digitization - "Smart Health“

Microelectronics as a key technology enables numerous innovations in the field of intelligent medical technology. The Fraunhofer Institute for Biomedical Engineering IBMT coordinates the BMBF cooperative project "I-call" realizing the first electronic system for ultrasound-based, safe and interference-resistant data transmission between implants in the human body.

When microelectronic systems are used for medical applications, they have to meet high requirements in terms of biocompatibility, reliability, energy...

Im Focus: When predictions of theoretical chemists become reality

Thomas Heine, Professor of Theoretical Chemistry at TU Dresden, together with his team, first predicted a topological 2D polymer in 2019. Only one year later, an international team led by Italian researchers was able to synthesize these materials and experimentally prove their topological properties. For the renowned journal Nature Materials, this was the occasion to invite Thomas Heine to a News and Views article, which was published this week. Under the title "Making 2D Topological Polymers a reality" Prof. Heine describes how his theory became a reality.

Ultrathin materials are extremely interesting as building blocks for next generation nano electronic devices, as it is much easier to make circuits and other...

Im Focus: Rolling into the deep

Scientists took a leukocyte as the blueprint and developed a microrobot that has the size, shape and moving capabilities of a white blood cell. Simulating a blood vessel in a laboratory setting, they succeeded in magnetically navigating the ball-shaped microroller through this dynamic and dense environment. The drug-delivery vehicle withstood the simulated blood flow, pushing the developments in targeted drug delivery a step further: inside the body, there is no better access route to all tissues and organs than the circulatory system. A robot that could actually travel through this finely woven web would revolutionize the minimally-invasive treatment of illnesses.

A team of scientists from the Max Planck Institute for Intelligent Systems (MPI-IS) in Stuttgart invented a tiny microrobot that resembles a white blood cell...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

Aachen Machine Tool Colloquium AWK'21 will take place on June 10 and 11, 2021

07.04.2020 | Event News

International Coral Reef Symposium in Bremen Postponed by a Year

06.04.2020 | Event News

 
Latest News

Black nitrogen: Bayreuth researchers discover new high-pressure material and solve a puzzle of the periodic table

29.05.2020 | Materials Sciences

Argonne researchers create active material out of microscopic spinning particles

29.05.2020 | Materials Sciences

Smart windows that self-illuminate on rainy days

29.05.2020 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>